Commit c8aa7038 authored by Stanislav Fomichev's avatar Stanislav Fomichev Committed by Daniel Borkmann
Browse files

net/flow_dissector: move bpf case into __skb_flow_bpf_dissect 



This way, we can reuse it for flow dissector in BPF_PROG_TEST_RUN.

No functional changes.

Signed-off-by: default avatarStanislav Fomichev <sdf@google.com>
Acked-by: default avatarSong Liu <songliubraving@fb.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent d76198b0

include/linux/skbuff.h

+5 −0
Original line number Diff line number Diff line
@@ -1221,6 +1221,11 @@ static inline int skb_flow_dissector_bpf_prog_detach(const union bpf_attr *attr) 
}

#endif



struct bpf_flow_keys;

bool __skb_flow_bpf_dissect(struct bpf_prog *prog,

			    const struct sk_buff *skb,

			    struct flow_dissector *flow_dissector,

			    struct bpf_flow_keys *flow_keys);

bool __skb_flow_dissect(const struct sk_buff *skb,

			struct flow_dissector *flow_dissector,

			void *target_container,

net/core/flow_dissector.c

+54 −38
Original line number Diff line number Diff line
@@ -683,6 +683,46 @@ static void __skb_flow_bpf_to_target(const struct bpf_flow_keys *flow_keys, 
	}

}



bool __skb_flow_bpf_dissect(struct bpf_prog *prog,

			    const struct sk_buff *skb,

			    struct flow_dissector *flow_dissector,

			    struct bpf_flow_keys *flow_keys)

{

	struct bpf_skb_data_end cb_saved;

	struct bpf_skb_data_end *cb;

	u32 result;



	/* Note that even though the const qualifier is discarded

	 * throughout the execution of the BPF program, all changes(the

	 * control block) are reverted after the BPF program returns.

	 * Therefore, __skb_flow_dissect does not alter the skb.

	 */



	cb = (struct bpf_skb_data_end *)skb->cb;



	/* Save Control Block */

	memcpy(&cb_saved, cb, sizeof(cb_saved));

	memset(cb, 0, sizeof(*cb));



	/* Pass parameters to the BPF program */

	memset(flow_keys, 0, sizeof(*flow_keys));

	cb->qdisc_cb.flow_keys = flow_keys;

	flow_keys->nhoff = skb_network_offset(skb);

	flow_keys->thoff = flow_keys->nhoff;



	bpf_compute_data_pointers((struct sk_buff *)skb);

	result = BPF_PROG_RUN(prog, skb);



	/* Restore state */

	memcpy(cb, &cb_saved, sizeof(cb_saved));



	flow_keys->nhoff = clamp_t(u16, flow_keys->nhoff, 0, skb->len);

	flow_keys->thoff = clamp_t(u16, flow_keys->thoff,

				   flow_keys->nhoff, skb->len);



	return result == BPF_OK;

}



/**

 * __skb_flow_dissect - extract the flow_keys struct and return it

 * @skb: sk_buff to extract the flow from, can be NULL if the rest are specified
@@ -714,7 +754,6 @@ bool __skb_flow_dissect(const struct sk_buff *skb, 
	struct flow_dissector_key_vlan *key_vlan;

	enum flow_dissect_ret fdret;

	enum flow_dissector_key_id dissector_vlan = FLOW_DISSECTOR_KEY_MAX;

	struct bpf_prog *attached = NULL;

	int num_hdrs = 0;

	u8 ip_proto = 0;

	bool ret;
@@ -754,53 +793,30 @@ bool __skb_flow_dissect(const struct sk_buff *skb, 
					      FLOW_DISSECTOR_KEY_BASIC,

					      target_container);



	rcu_read_lock();

	if (skb) {

		struct bpf_flow_keys flow_keys;

		struct bpf_prog *attached = NULL;



		rcu_read_lock();



		if (skb->dev)

			attached = rcu_dereference(dev_net(skb->dev)->flow_dissector_prog);

		else if (skb->sk)

			attached = rcu_dereference(sock_net(skb->sk)->flow_dissector_prog);

		else

			WARN_ON_ONCE(1);

	}

	if (attached) {

		/* Note that even though the const qualifier is discarded

		 * throughout the execution of the BPF program, all changes(the

		 * control block) are reverted after the BPF program returns.

		 * Therefore, __skb_flow_dissect does not alter the skb.

		 */

		struct bpf_flow_keys flow_keys = {};

		struct bpf_skb_data_end cb_saved;

		struct bpf_skb_data_end *cb;

		u32 result;



		cb = (struct bpf_skb_data_end *)skb->cb;



		/* Save Control Block */

		memcpy(&cb_saved, cb, sizeof(cb_saved));

		memset(cb, 0, sizeof(cb_saved));



		/* Pass parameters to the BPF program */

		cb->qdisc_cb.flow_keys = &flow_keys;

		flow_keys.nhoff = nhoff;

		flow_keys.thoff = nhoff;



		bpf_compute_data_pointers((struct sk_buff *)skb);

		result = BPF_PROG_RUN(attached, skb);



		/* Restore state */

		memcpy(cb, &cb_saved, sizeof(cb_saved));



		flow_keys.nhoff = clamp_t(u16, flow_keys.nhoff, 0, skb->len);

		flow_keys.thoff = clamp_t(u16, flow_keys.thoff,

					  flow_keys.nhoff, skb->len);



		if (attached) {

			ret = __skb_flow_bpf_dissect(attached, skb,

						     flow_dissector,

						     &flow_keys);

			__skb_flow_bpf_to_target(&flow_keys, flow_dissector,

						 target_container);

			rcu_read_unlock();

		return result == BPF_OK;

			return ret;

		}

		rcu_read_unlock();

	}



	if (dissector_uses_key(flow_dissector,

			       FLOW_DISSECTOR_KEY_ETH_ADDRS)) {